Antireflection filter for display device

ABSTRACT

A display device antireflection filter  100  formed on a glass base material is comprised of an antireflection layer  102  of at least one layer containing SiO 2  and a material layer  103  made of composition produced by adding compound whose interaction with SiO 2  is small to compound having alkoxysilane group at terminal and which has perfluoropolyether group. This device exhibits improved wear and abrasion resistance.

RELATED APPLICATION DATA

[0001] The present application claims priority to Japanese ApplicationNo. P2000-102413 filed Apr. 4, 2000, which application is incorporatedherein by reference to the extent permitted by law.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an antireflection filter for adisplay device.

[0004] 2. Description of the Related Art

[0005] When a viewer watches something through a transparent materialsuch as glass, reflected light on the glass surface is strong so that,if a reflected image is clear, then a viewer will be troubled.

[0006] For example, a reflected image such as so-called ghost and flareis produced on lenses for glasses and a viewer will be troubled.

[0007] Furthermore, it is frequently observed that a user cannot clearlysee contents through a looking-glass or the like due to light reflectedon the glass surface.

[0008] When a problem that a sense of sight is troubled by reflectedlight is solved, in order to prevent reflection, heretofore, there hasbeen proposed a method in which an antireflection layer is formed bycoating a material having a different refractive index on a basematerial by vacuum deposition or the like.

[0009] In this method, there is known that an antireflection effect canbe increased by properly setting a thickness of an antireflection layerformed on the base material.

[0010] For example, when this antireflection layer is formed as a singlelayer structure, in order to minimize a reflectance or to maximize atransmittance, it is effective to use a material having a lowerrefractive index than a base material of an underlayer and to select anoptical film thickness to be ¼ of wavelength of light or to beodd-numbered times of ¼.

[0011] Here, the optical film thickness is given by the product of therefractive index of the material for forming a coated film and a filmthickness of the coated film.

[0012] It is proposed that an antireflection layer is formed as amultilayer structure. In this case, there are various proposals withrespect to selection of a film thickness of an antireflection layer(OPTICAL TECHNOLOGY Vol. No. 8, p17 (1971)).

[0013] On the other hand, Japanese laid-open patent application No.58-46301 and Japanese laid-open patent application No. 59-49501 haveproposed methods in which a multilayer structure antireflection layerwhich can satisfy a condition of the above optical film thickness byusing liquid composition.

[0014] In recent years, there are proposed optical products havingantireflection property in which plastics material is used as a basematerial by effectively utilizing good points in which plastics materialis light in weight, safe and is easy to handle. These optical productshave been put into practice. Most of the optical products have anantireflection layer made of a material containing silicon dioxideformed on the surface.

SUMMARY OF THE INVENTION

[0015] However, when the antireflection layer is deposited on the abovebase material by vacuum deposition, as the material of thisantireflection layer, there are mainly used inorganic oxide or inorganichalogenide.

[0016] When glass is used as the base material, there arises a problemthat, although the antireflection layer of the upper layer has highsurface hardness, when it is smudged by user's finger marks, fingerprints, sweat, liquid hair tonic, hair spray or the like, smudges areconspicuous and these smudges are difficult to be removed.

[0017] Since such antireflection layer is poor in surface smoothness, itis easy to be scratched conspicuously. Further, since suchantireflection layer has large wetting against water, when it is smudgedby raindrops or splashes of other water, large marks are easily left onthe surface of the antireflection layer. In particular, there arises aproblem that, when a user watches an object through glasses, the objectis distorted over a large area.

[0018] In the antireflection layers described in the above Japaneselaid-open patent application No. 58-46301, the above Japanese laid-openpatent application No. 59-49501 and Japanese laid-open patentapplication No. 59-50401, there are described technologies in which theuppermost layer contains more than 30 [parts by weight] of inorganicmaterial represented by silica fine-grained particles provide a highsurface hardness. The antireflection layer obtained by the abovecomposition encounters with a problem that it becomes poor in surfacesmoothness, it is easy to be scratched by friction of clothes or thelike and its scratches become conspicuous.

[0019] In order to improve the above problems, there are proposed andappear on the market various surface finishing agents.

[0020] However, since any these surface finishing agents are dissolvedby water and various solvents, even when the surface of theantireflection layer is treated by the surface finishing agent, thesurface finishing effect is not lasting and is therefore poor indurability.

[0021] Japanese laid-open patent application No. 3-266801 has proposed atechnology in which a fluororesin layer is formed to provide waterrepellent property. However, although the water repellent property canbe provided by using the fluororesin, satisfactory results of durabilitywith respect to friction and abrasion on the surface could not beobtained yet.

[0022] In order to improve durability with respect to friction andabrasion on the surface and to solve a problem of pollution resistance,there is proposed a technology in which an antireflection layer issurface-finished by perfluoropolyether compound (Japanese patentapplication No. 7-224063).

[0023] However, in the technology proposed by the above Japanese patentapplication No. 7-224063, since a chemical stability of surfacefinishing agent is not satisfactory, there arises a problem thatantireflection effect of the surface is considerably deteriorated by atreatment with a solvent or the like Japanese laid-open patentapplication No. 9-61605 has proposed a technology in which a problem ofwear and abrasion resistance or pollution resistance of a display devicefilter having antireflection property can be solved by coating thesurface with alkoxysilane compound having perfluoropolyether group.

[0024] In the technology proposed in the Japanese laid-open patentapplication No. 9-61605, in order to enable SiO2 component in the glassof the underlayer of the antireflection layer and a material used toform the antireflection layer to interact with each other, a stronglinkage with the SiO₂ component can be formed by causing molecularstructure to contain alkoxysilane group.

[0025] However, in the antireflection layer proposed in this Japaneselaid-open patent application No. 9-61605, having considered thisantireflection layer from a wear and abrasion resistance standpoint, itis to be understood that this antireflection layer has rooms to beimproved in characteristic.

[0026] Specifically, in the antireflection layer proposed in theJapanese laid-open patent application No. 9-61605, since thealkoxysilane compound chemically reacts with the SiO2 component, thesurface of this material has no migration. Consequently, when frictioncontact occurs in actual practice, if this material is removed from theportion in which the friction contact occurred, then such damagedportion will not be restored by movement of materials from itsperiphery.

[0027] Accordingly, after earnest researches, the assignee of thepresent application proposes an antireflection filter for display devicein which the above problems can be solved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028]FIG. 1 is a schematic diagram showing an arrangement of an exampleof a display device which is applied to an antireflection filter fordisplay device according to the present invention.

[0029]FIG. 2 is a schematic diagram showing an arrangement of an exampleof an antireflection filter for display device according to the presentinvention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0030] An antireflection filter for display device according to thepresent invention is an antireflection filter for display device formedon a glass base material. An antireflection filter for display devicehas an antireflection layer of at least one layer containing Sio₂ and amaterial layer made of composition produced by adding compound whoseinteraction with SiO₂ is small to compound having alkoxysilane group atterminal and having perfluoropolyether group and which is expressed bythe following [Formula 2] formed on the antireflection layer.

[0031] [Formula 2]

R_(f)COR₁—R₂—Si(OR3)₃

[0032] (R_(f) represents perfluoropolyether group

[0033] R₁ represents any one of O, NH, S

[0034] R2 represents alkylene chain

[0035] R3 represents alkyl group)

[0036] According to the antireflection filter for display device of thepresent invention, since the material layer formed of the compositionproduced by adding the compound whose interaction with SiO₂ is small tothe compound having alkoxysilane group at terminal andperfluoropolyether group and which is expressed by the above [Formula 2]is formed on the antireflection layer of at least one layer containingSiO₂, the material layer becomes able to flow on the antireflectionlayer microscopically. Thus, when friction contact occurs on the surfaceof the material layer, if this material is removed from such portion,then the portion from which this material was removed can be restored bythe movement of the material from its periphery, and hence the wear andabrasion resistance on the surface of the display device could beimproved.

[0037] An antireflection filter for display device according to thepresent invention is an antireflection filter for display device formedon a glass base material. An antireflection filter for display devicehas an antireflection layer of at least one layer containing SiO₂ and amaterial layer made of composition produced by adding compound whoseinteraction with SiO₂ is small to compound having alkoxysilane group atterminal and having perfluoropolyether group and which is expressed bythe following [Formula 3] on the antireflection layer.

[0038] [Formula 3]

R_(f)COR₁—R₂—Si(OR₃)₃

[0039] (R_(f) represents perfluoropolyether group

[0040] R₁ represents any one of O, NH, S

[0041] R₂ represents alkylene chain

[0042] R₃ represents alkyl group)

[0043] An antireflection filter for display device according to anembodiment of the present invention will be described below. However, anantireflection filter for display device according to the presentinvention is not limited to an antireflection filter which will bedescribed below.

[0044] As an object of a target to which a display device antireflectionfilter 100 according to the present invention is applied, FIG. 1 shows afundamental arrangement of a main portion of a display device 1 using acathode-ray tube (hereinafter referred to as a “CRT”), e.g., monochromeCRT.

[0045] As shown in FIG. 1, a CRT 1 a includes a panel portion 2 whoseinside is evacuated and in which a fluorescent material is coated on theinner surface, a funnel portion 3 in which an electron beam travelingspace is held at an equal potential by a conductive film coated on theinner surface and which forms a smoothing capacitor of a high withstandvoltage with a conductive film formed on the outer surface and a neckportion 5 in which an electron gun 6 is disposed.

[0046] A video signal VD supplied to a terminal 12 is amplified by avideo amplifier 10 and supplied to the electron gun 6. An electron beameb responsive to the video signal VD is emitted from the electron gun 6.A deflection circuit 11 drives a deflection yoke 4 in response tohorizontal and vertical synchronizing signals obtained from the videosignal VD by the video amplifier 10. The electron beam eb emitted fromthe electron gun 6 is deflected in trajectory by a magnetic fieldgenerated from the deflection yoke 4 driven by the above deflectioncircuit 11 and scans the fluorescent screen formed on the inner surfaceof the above panel portion 2 so that phosphor on this fluorescent screenis energized to emit light. The direction in which the electron beam ebscans the fluorescent screen in the case of FIG. 1 is perpendicular tothe sheet of drawing.

[0047] While the display device antireflection filter 100 according tothe present invention is formed on the surface of the panel portion 2comprising the display device 1 as shown in FIG. 1, it can be directlydeposited on the surface of the panel portion 2 by coating materials orit can be formed by attaching a film-like product in which materials arecoated on a predetermined transparent base material such as polyethyleneterephthalate film on the surface of the panel portion 2.

[0048] Next, the display device antireflection filter 100 according tothe present invention will be described with reference to a schematiccross-sectional view.

[0049] The display device antireflection filter 100 shown in FIG. 2includes an antireflection layer 102 of at least one layer on atransparent base material 101, and a material layer 103 made ofcomposition produced by adding compound whose interaction withpredetermined SiO2 is small to the compound expressed by the above[Formula 1] is formed on this antireflection layer 102.

[0050] As the transparent base material 101 shown in FIG. 2, there canbe applied polyethylene terephthalate (PET) film of 188 [μm], forexample.

[0051] The antireflection layer 102 on the transparent base material 101includes a film made of at least one layer of SiO2 .

[0052] When this antireflection layer 102 has a multilayer structure,the uppermost layer includes an SiO₂ film.

[0053] At that time, the SiO₂ film of the uppermost layer candemonstrate an antireflection effect at maximum because a minimumreflectance, i.e., maximum transmittance can be realized by selectingthis optical film thickness n to be n=(¼)k or odd-numbered times where Xrepresents a wavelength of target light.

[0054] With respect to a film formed under the SiO₂ film of theuppermost layer comprising the antireflection layer 102, there can beapplied respective kinds of inorganic materials in addition to SiO₂.

[0055] Specifically, inorganic materials such as Al₂O₃, ZrO₂, TiO₂,Ta₂O₅, SiO, HfO₂, ZnO, In₂O₃/SnO₂, TiO, Ti₂O₃, Y₂O₃, Sb₂O₃, MgO, CeO₂can be used properly.

[0056] By forming the layer of respective kinds of inorganic materialson the underlayer of the uppermost layer comprising the antireflectionlayer 102 as described above, there can be improved thermal resistance,antireflection property, reflected light color, durability, surfacehardness, and the like.

[0057] With respect to the selection of film thickness and refractiveindex of the antireflection layer having the multilayer structure, therehave been made various proposals (OPTICAL TECHNOLOGY CONTACT Vol. 9, No.9, pp 17 [1971]).

[0058] As a coating method of various kinds of inorganic materialsincluding SiO₂ comprising the antireflection layer 102, there can beapplied any of conventional PVD method (Physical Vapor Depositionmethod) such as vacuum deposition, ion plating and sputtering.

[0059] Next, the material layer 103 formed on the antireflection layer102 will be described.

[0060] This material layer 103 is formed by composition produced byadding compound whose interaction with Sio₂ is small to compound havingalkoxysilane group at terminal and perfluoropolyether group and which isexpressed by the following [Formula 4].

[0061] [Formula 4]

R_(f)COR₁—R₂—Si(OR₃)₃

[0062] (R_(f) represents perfluoropolyether group

[0063] R₁ represents any of O, NH, S

[0064] R₂ represents alkylene chain

[0065] R₃ represents alkyl group)

[0066] While there are enumerated those having structures expressed bythe following [Formula 5] to [Formula 7] as concrete examples of theabove perfluoropolyether group (R_(f)), they are not limited to thefollowing ones.

[0067] [Formula 7]

F(OCF₂CF₂)_(k)—

[0068] Here, l, m, n, k in the chemical structures of the aboveperfluoropolyether group (R_(f)) are integers of greater 1,respectively.

[0069] Moreover, as multifunctional perfluoropolyether, there isenumerated such one expressed by the following [Formula 8], by way ofexample.

[0070] [Formula 8]

—(OCF₂)_(p)(CF₂CF₂O)_(q)—

[0071] Here, in the chemical structure of the above multifunctionalperfluoropolyether, p and q are integers of greater than 1 and p/qshould preferably be selected in a range of from 0.5 to 2.

[0072] “Compound whose interaction with SiO₂ is small” used to makecomposition comprising the material layer 103 is defined as compound forproducing a material remaining ratio of less than 50[%] obtained whenthe material layer 103 was wiped away by an absorbent cotton containingethanol about 20 times under pressure of 1 [kg/cm²] and the materialremaining ratios were measured after the material layer 103 had beenformed finally.

[0073] As concrete examples of compounds whose interaction with SiO₂ issmall, there are enumerated those expressed by the following [Formula 9]to [Formula 13].

[0074] [Formula 10]

CF₃O(CF₂O)_(n)(CF₂CF₂O)_(m)CF₂OCF₃

[0075]

[0076] [Formula 12]

C₁₇H₃₅COOCH₃

[0077] [Formula 13]

C₁₈H₃₇NH₂

[0078] A number-average molecular weight of compound used to form thematerial layer 103 comprising the display device antireflection filter100 according to the present invention and which has alkoxysilane groupat terminal and perfluoropolyether group should preferably be selectedin a range of about 500 to 10000 considering chemical stability andfacilitating the treatment. More preferably, the above number-averagemolecular weight should be selected in a range of from about 700 to5000.

[0079] A number-average molecular weight of compound whose interactionwith SiO₂ is small should be selected in a range of from 500 to 10000when compound is perfluoropolyether compound, and more preferably shouldbe selected in a range of from 500 to 5000.

[0080] The reason for this is that, if a number-average molecular weightof perfluoropolyether compound is less than 500, then when the materiallayer 103 is finally formed, wear and abrasion resistance effect cannotbe obtained satisfactorily. If compound has a number-average molecularweight exceeding 10000, such compound is very difficult to obtain ascommercially-available compounds. Furthermore, compound having anumber-average molecular weight exceeding 5000 is costly when it issynthesized industrially.

[0081] From an industrial standpoint, there can be used compounds havingnumber-average molecular weights of about 2000 to 3000 which are easy toobtain.

[0082] The display device antireflection filter 100 according to thepresent invention may not include the transparent material 101 and maybe formed by directly depositing the antireflection layer 102 and thematerial layer 103 on the display screen of the cathode-ray tube 1 ashown in FIG. 1.

[0083] The material layer 103 should have a thickness of approximatelyseveral [nm]. To this end, a concentration of a material coated to formthe material layer 103 should be selected in a range of from 0.1 to 5[wt %].

[0084] When in use, compositions used to form the material layer 103 aregenerally diluted by volatile solvent. In this case, while conventionalsolvents are used as solvent to dilute compositions, consideringwetting, volatility for silicon dioxide of the underlayer of thematerial layer 103 or the like, fluorinated solvent whose surface energyis low should preferably be used.

[0085] While a film thickness of the material layer 103 should be lessthan 100 [nm], to secure antireflection and from a relationship betweenbalance of rest contact angle for water and surface hardness, it shouldpreferably be selected in a range of from about 0.5 to 10 [nm].

[0086] The material layer 103 can be formed by conventional coating. Inparticular, to maintain homogeneity of antireflection effect and tofacilitate control of reflected interference color, there are appliedspin coat, dip coating, curtain-flow coating and the like. Furthermore,there can be applied a method in which a paper, a cloth or the like isimpregnated with coating liquid useful for forming the material layer103 and the coating liquid is thereby coated and flowed.

[0087] As a glass base material for forming the display deviceantireflection filter 100 according to the present invention, there canbe used any one of soda glass, lead glass, hard glass, quartz glass andliquid-crystal glass (e.g., Basics of Chemical Handbook, P.1-537, editedby The Japan Society of Chemistry). Further, a CRT uses silicate glasscontaining strontium and barium, and a liquid-crystal display deviceuses nonalkaline glass. Any one of these glasses can be applied to theantireflection filter for display device according to the presentinvention, and any of other glasses made of conventional materials alsocan be applied thereto.

[0088] The surface of the antireflection layer 102 which is used to formthe material layer 103 comprising the display device antireflectionfilter 100 according to the present invention should be cleansed inadvance.

[0089] When the surface of the antireflection layer 102 is cleansed,there are enumerated methods in which smudges are removed by surfactant,the surface is degreased by organic solvent and cleansed by steam basedon Freon.

[0090] In order to improve adhesion with the antireflection layer 102and the material layer 103 and in order to improve durability of thematerial layer 103, as a pretreatment of a coating process, theantireflection layer 102 can be treated by activated gas treatment anddrug treatment based on acid and alkali, and the like.

[0091] Next, the antireflection filter for display device according tothe present invention will be described with reference to concreteexamples, but the antireflection filter for display device according tothe present invention are not limited to the following respectiveexamples.

[0092] First, on the display screen 2 which is the panel portion of thecathode-ray tube (CRT) shown in FIG. 1, there was formed an ITO(tin-oxide doped indium, Indium Tin Oxide) film having a thickness ofabout 130 [nm] by sputtering on which SiO₂ film having a thickness ofapproximately 80 [nm] was deposited as the antireflection layer 102 byvapor deposition.

[0093] Next, there were prepared compounds having alkoxysilane group atterminal and which has perfluoropolyether group. [Table 1] showsstructures of [compound 1] to [compound 3] having alkoxysilane group asterminal and which have perfluoropolyether group. TABLE 1 structuralformula compound 1

compound 2 (C₂H₅O)₃SiC₃H₆NHCOCF₂O(CF₂O)₂(CF₂CF₂O)_(m)CF₂CONHC₃H₆Si(OC₂H₅)₃ compound 3 C₃F₇(OCF₂CF₂CF₂)₆(OCF₂)₂[CH₂CHSi(OCH₃)₃]₁₋₁₀

[0094] where 1 is an integer from 11 to 30, n/m is 0.5 to 2 and whosenumber-average molecular weight is 500 to 10000 and s is an integer from10 to 30.

[0095] Next, as compounds which are to be added to the [compound 1] tothe [compound 3] on the [Table 1], there are prepared compounds whoseinteraction with the SiO₂ layer of the underlayer is small.

[0096] Structures of [compound 4] to [compound 8] whose interaction withthe SiO₂ layer is small used in this embodiment are shown on [Table 2].TABLE 2 structural formula compound 4

compound 5 CF₃O(CF₂O)_(n)(CF₂CF₂)_(m)CF₂OCF₃ compound 6HOCH₂CF₂O(CF₂O)_(n)(CF₂CF₂O)_(m)CF₂OCF₂CH₂OH compound 7 C₁₇H₃₅COOCH₃compound 8 C₁₈H₃₇NH₂

[0097] where n/m is 0.2 to 2, number-average molecular weights of the[compound 4] to the [compound 8] are 500 to 10000 and 1 is an integerfrom 10 to 60.

[0098] Composition 1 to composition 14 shown on the following Table 3were made by properly combining and adding the compound 1 to thecompound 3 shown on the Table 1 to the compound 4 to the compound 8shown on the Table 2.

[0099] Ratios of respective compounds comprising these composition 1 tocomposition 14, i.e., ratios of compounds in the Table 1/compounds inthe Table 2 are indicated on the [Table 3.

[0100] As shown on the Table 3, the ratios of composition 1 tocomposition 13 should be selected in a range of from 100/60 to 100/3 andthe ratio of composition 14 should be selected to be outside of theabove range. TABLE 3 compound on compound on compound on [Table1]/compound composition [Table 1] [Table 2] on [Table 2] composition 1compound 1 compound 5 100/25 composition 2 compound 1 compound 6 100/25composition 3 compound 1 compound 7 100/25 composition 4 compound 1compound 8 100/25 composition 5 compound 2 compound 4 100/25 composition6 compound 2 compound 5 100/25 composition 7 compound 3 compound 6100/25 composition 8 compound 3 compound 7 100/25 composition 9 compound1 compound 4 100/3  composition compound 1 compound 4 100/10 10composition compound 1 compound 4 100/20 11 composition compound 1compound 4 100/50 12 composition compound 1 compound 4 100/60 13composition compound 1 compound 4  100/100 14

[0101] Next, after the composition 1 to the composition 14 had beendiluted into homogeneous solution of 0.1 to 5 [weight %] by mixing 200[parts by weight] of alcohol to 4 [parts by weight] of thesecompositions, solutions were filtered by a membrane filter, for example,and thereby a coating material was made.

[0102] Next, the material layer 103 was made by coating the abovematerial on the antireflection layer 102 at a lifting rate of 5[cm/min], for example, by dip coating.

[0103] Next, properties of the above display device antireflectionfilters thus made will be evaluated. Samples made by respectively usingthe composition 1 to the composition 13 thus made were referred to as a“[inventive example 1]” to a “[inventive example 13]”.

[0104] As a target to be compared, a sample which was made withoutforming the material layer 103 was referred to as a “[comparativeexample 1]”.

[0105] Further, a sample in which the material layer 103 was formed byusing only the compound 1 was referred to as a “[comparative example2]”. A sample in which the material layer 103 was formed by using onlythe “[compound 6]” was referred to as a “[comparative example 3]”. Asample in which the material layer 103 was formed by using only the“[compound 5]” was referred to as a [comparative example 4”]. A samplein which the material layer was formed by using the composition 14 onthe Table 3 was referred to as a “[comparative example 5]”.

[0106] Evaluation methods for evaluating characteristics of the abovesamples are shown on the following (1) to (5).

[0107] (1) Pollution resistance test:

[0108] Water of 5 [ml] was dropped on the surfaces of the respectivesamples manufactured by the above manner. After these samples had beenleft under ordinary temperature atmosphere for 48 hours, they were wipedaway by a cloth and the states in which fur was remaining on thesurfaces of the samples were observed. The state in which fur could beremoved sufficiently was evaluated as “satisfactory”, and the state inwhich fur could not be removed sufficiently was evaluated as “poor”.

[0109] This pollution resistance test was evaluated before and after thesurfaces of the respective samples were rinsed by ethyl alcoholsolution, respectively.

[0110] (2) Surface smoothness:

[0111] The surfaces of the respective samples were scratched by a pointof a commercially-available mechanical pencil with a load of 300 [g].Evaluation standards are as follows:

[0112] Not being scratched at all: ∘

[0113] Being scratched with an increase of a load: Δ

[0114] Being scratched even though a load is decreased: ×

[0115] This surface smoothness was respectively evaluated before andafter the surfaces of the respective samples were rinsed by ethylalcohol solution.

[0116] (3) Wear and abrasion resistance test:

[0117] After the surfaces of the respective samples were rubbed by apredetermined glass wool (#0000) with a load of 300 [g] 30 times, theoccurrence of scratches was evaluated. Evaluation standards are asfollows:

[0118] Not being scratched at all: ∘

[0119] Being scratched finely: Δ

[0120] Scratched considerably: ×

[0121] This wear and abrasion resistance test was respectively evaluatedbefore and after the surfaces of the respective samples were rinsed byethyl alcohol solution.

[0122] (4) Evaluation of degree of being difficult to be smudged byfinger marks:

[0123] Degrees at which the surfaces of the respective samples aredifficult to be smudged by finger marks were evaluated visually.Evaluation standards are as follow:

[0124] Finger marks on the surface are inconspicuous: ∘

[0125] Finger marks on the surface can be eliminated easily: Δ

[0126] Finger marks on the surface are conspicuous: ×

[0127] The degrees at which the surfaces of the respective samples aredifficult to be smudged by finger marks were evaluated before and afterthe surfaces of the respective samples were rinsed by ethyl alcoholsolution, respectively.

[0128] (5) Contact angle test:

[0129] By measuring contact angles of water (H₂O) and methylene iodide(CH₂ I₂), there can be obtained standards for a remaining ratio of alubrication film and pollution against water and oil. Specifically, itcan be evaluated that the sample in which the contact angle is small isexcellent in wetting and is therefore easy to be polluted. It can alsobe evaluated that the sample in which the contact angle is large isexcellent in water repellent property and oil repellent property and istherefore difficult to be polluted.

[0130] This contact angle test was evaluated before and after thesurfaces of the respective samples were rinsed by ethyl alcoholsolution, respectively.

[0131] Evaluated results of the above evaluations (1) to (5) are shownon the following [Table 4]. TABLE 4 wear and abrasion Degree of beingcontact angle (deg.) pollution surface resistance difficult to besmudged H₂O CH₂I₂ H₂O CH₂I₂ composition resistance smoothness test byfinger marks before being after being composition or compound beforeafter before after before after before after rinsed by ethanol rinsed byethanol inventive composition satis- satis- ∘ ∘ ∘ ∘ ∘ ∘ 110 90 109 89example 1 1 factory factory inventive composition satis- satis- ∘ ∘ ∘ ∘∘ ∘ 109 91 110 90 example 2 2 factory factory inventive compositionsatis- satis- ∘ ∘ ∘ ∘ ∘ ∘ 111 91 111 90 example 3 3 factory factoryinventive composition satis- satis- ∘ ∘ ∘ ∘ ∘ ∘ 109 88 109 88 example 44 factory factory inventive composition satis- satis- ∘ ∘ ∘ ∘ ∘ ∘ 111 89110 88 example 5 5 factory factory inventive composition satis- satis- ∘∘ ∘ ∘ ∘ ∘ 110 90 110 90 example 6 6 factory factory inventivecomposition satis- satis- ∘ ∘ ∘ ∘ ∘ ∘ 115 94 114 93 example 7 7 factoryfactory inventive composition satis- satis- ∘ ∘ ∘ ∘ ∘ ∘ 113 92 112 92example 8 8 factory factory inventive composition satis- satis- ∘ ∘ ∘ ∘∘ ∘ 115 94 112 92 example 9 9 factory factory inventive compositionsatis- satis- ∘ ∘ ∘ ∘ ∘ ∘ 112 92 107 87 example 10 10 factory factoryinventive composition satis- satis- ∘ ∘ ∘ ∘ ∘ ∘ 109 90 101 84 example 1111 factory factory inventive composition satis- satis- ∘ ∘ ∘ ∘ ∘ ∘ 10487  97 80 example 12 12 factory factory inventive composition satis-satis- ∘ ∘ ∘ ∘ ∘ ∘ 102 85  93 78 example 13 13 factory factorycomparative none poor poor x x x x x x  37 53 — — example 1 comparativecompound 1 satis- satis- ∘ ∘ x x ∘ ∘ 114 93 112 92 example 2 factoryfactory comparative compound 6 satis- poor ∘ x ∘ x Δ x 102 87  32 53example 3 factory comparative compound 5 poor poor Δ x ∘ x Δ x  96 76 30 51 example 4 comparative composition satis- poor ∘ Δ ∘ Δ ∘ Δ 103 86 94 78 example 5 14 factory

[0132] As shown on the Table 4, with respect to the antireflectionfilters for display device having the SiO₂ antireflection layer on theglass base material and material layers formed of the composition 1 tothe composition 13, on the Table 3, produced by adding compounds on theTable 2 whose interaction with SiO₂ is small to compounds on the Table 1having alkoxysilane group at terminal and which has perfluoropolyethergroup, there had been obtained excellent evaluated results in the aboveevaluations (1) to (5).

[0133] In particular, with respect to the evaluations of the wear andabrasion resistance, while any of the comparative example 1 to thecomparative example 5 has demonstrated deterioration on the evaluationsobtained after being rinsed by ethyl alcohol solution, any one of thesamples of the inventive example 1 to the inventive example 13 has nodeterioration of the wear and abrasion resistance.

[0134] In the sample of the comparative example 1 in which the materiallayer 103 is not formed on the antireflection layer 102, there could notbe obtained satisfactory results with respect to any of the evaluationsof the pollution resistance, the surface smoothness, the wear andabrasion resistance test and the degree of being difficult to be smudgedby finger marks. With respect to the contact angle of water (H₂O) andmethylene iodide (CH₂ I₂), it was understood that the sample of thiscomparative example is very small contact angle as compared with othersamples and is therefore easy to be polluted by water and oil.

[0135] In the sample of the comparative example 2 in which only thecompound 1 on the Table 1 was used and the compound on the Table 2 wasnot added, there could not be obtained a satisfactory evaluated resultof the wear and abrasion resistance test.

[0136] In the sample of the comparative example 3 in which the compound6 on the Table 2 was used and the compound on the Table 1 was not used,there could not be obtained a satisfactory result of any of theevaluations of the pollution resistance, the surface smoothness, thewear and abrasion resistance, the degree of being difficult to besmudged by finger marks and the contact angle which were measured afterthe surface of the sample was rinsed by ethanol solution.

[0137] In the sample of the comparative example 4 in which only thecompound 5 on the Table 2 was used and the compound on the Table 1 wasnot used, there could not be obtained satisfactory results of therespective evaluations of the pollution resistance, the surfacesmoothness measured after the surface of the sample was rinsed byethanol solution, the wear and abrasion resistance, the degree of beingdifficult to be smudged by finger marks and the contact angle.

[0138] As shown on the Table 3, having compared the inventive example 9to the inventive example 13 in which the material layer 103 was formedby both of the compound 1 and the compound 4 with the comparativeexample 5, it was understood that, while the inventive example 9 to theinventive example 13 in which the ratio of (compound 1/compound 4) was(100/60) to (100/3) could obtain desired practical results of any of theevaluations of the pollution resistance, the surface smoothness, wearand abrasion resistance test, the degree of being difficult to besmudged by finger marks and the contact angle test, the comparativeexample 5 using the composition 14 in which the ratio of (compound1/compound 4) is outside the above range could not obtain preferableresults of any of the evaluations of the pollution resistance measuredafter the surface of the sample was rinsed by ethanol solution, thesurface smoothness, the wear and abrasion resistance and the degree ofbeing difficult to be smudged by finger marks. From the above, it willbe appreciated that there should be used the composition in which 3 to60 [parts by weight] of the above compound whose interaction with SiO₂is small are added to 100 [parts by weight] of the compound havingalkoxysilane group at terminal and which has perfluoropolyether group.

[0139] As described above, according to the antireflection filter fordisplay device of the present invention, since the material layer formedof the composition produced by adding the compound whose interactionwith SiO₂ is small to the compound having alkoxysilane group at terminaland perfluoropolyether group and which is expressed by the above Formula1 is formed on the antireflection layer of at least one layer containingSiO₂, the material layer becomes able to flow on the antireflectionlayer microscopically. Thus, when a friction contact occurs on thesurface of the material layer in actual practice, if this material isremoved from such portion, then the portion from which this material isremoved can be restored by the movement of the material from itsperiphery, and hence the wear and abrasion resistance on the surface ofthe display device could be improved.

[0140] The antireflection filter for display device of the presentinvention can be effectively avoided from being smudged. Even when theantireflection filter for display device of the present invention issmudged, such smudges are inconspicuous and can be removed with ease.

[0141] Further, since the surface of the antireflection filter fordisplay device of the present invention is excellent in surfacesmoothness, the surface is difficult to be scratched and is alsoexcellent in durability of wear and abrasion resistance.

[0142] According to the antireflection filter for display device of thepresent invention, since the material layer formed of the compositionproduced by adding the compound whose interaction with SiO₂ is small tothe compound having alkoxysilane group at terminal andperfluoropolyether group and which is expressed by the above Formula 1is formed on the antireflection layer of at least one layer containingSiO₂, the material layer becomes able to flow on the antireflectionlayer microscopically. Thus, when a friction contact occurs on thesurface of the material layer in actual practice, if this material isremoved from such portion, then the portion from which this material isremoved can be restored by the movement of the material from itsperiphery, and hence the wear and abrasion resistance on the surface ofthe display device could be improved.

[0143] The antireflection filter for display device of the presentinvention can be effectively avoided from being smudged. Even when theantireflection filter for display device of the present invention issmudged smudges, such smudges are inconspicuous and can be removed withease.

[0144] Further, since the surface of the antireflection filter fordisplay device of the present invention is excellent in surfacesmoothness, the surface is difficult to be scratched and is alsoexcellent in durability of wear and abrasion resistance.

1. In an antireflection filter for display device formed on a glass basematerial, said antireflection filter for display device characterized byat least one antireflection layer containing Sio₂ and a material layermade of a composition produced by adding compound having smallinteraction with said SiO₂ to compound having alkoxysilane group atterminal and perfluoroether group and which is expressed by thefollowing formula 1 on said antireflection layer: R_(f)COR₁—R₂—Si(OR₃)₃(R_(f) represents perfluoropolyether group) R₁ represents any one of O,NH, S R₂ represents alkylene chain R_(s) represents alkyl group
 2. Anantireflection filter for display device according to claim 1, whereinsaid compound whose interaction with said SiO₂ is small isperfluoropolyether.
 3. An antireflection filter for display deviceaccording to claim 1, wherein said antireflection layer is formed on atransparent base material.
 4. An antireflection filter for displaydevice according to claim 1, wherein 3 to 60 parts by weight of saidcompound whose interaction with said SiO₂ is small are added to 100parts by weight of said compound expressed by said formula
 1. 5. Anantireflection filter for display device according to claim 1, whereinnumber-average molecular weight of said compound whose interaction withsaid SiO₂ is small falls in a range of from 500 to
 5000. 6. Anantireflection filter for display device according to claim 1, whereinsaid SiO₂ layer in at least one antireflection layer containing saidSiO₂ has an optical film thickness of n=(¼)λ (or an optical filmthickness of odd-numbered times of said n=(¼)λ (where n represents theoptical film thickness and λ represents the wavelength of target light.7. An antireflection filter for display device according to claim 1,wherein number-average molecular weight of said compound havingalkoxysilane group at terminal and perfluoroether group falls in a rangeof 700 to
 5000. 8. An antireflection filter for display device accordingto claim 1, wherein said coating material for forming said materiallayer has a concentration ranging from 0.1 to 5 (weight %).
 9. Anantireflection filter for display device according to claim 1, wherein said material layer has a film thickness ranging from 0.5 to 10 (nm).